Dark excitons can make a high contribution to light emission from nanotubes

Figure 1: Schematic drawing showing a dark exciton converting into a bright exciton before emitting light. Three RIKEN physicists have shown that the conversion rate of this process is higher in longer nanotubes. Credit: A. Ishii et al. CC BY 4.0 © 2019

Tailoring the dimensions and other attributes of carbon nanotubes can substantially boost the amount of light they emit, three physicists at RIKEN have discovered. This finding promises to lead to the development of highly efficient photonic devices.

Carbon nanotubes are tiny cylinders that are just a nanometer to a few nanometers in diameter but can be up to several micrometers in length. Their excellent electronic and mechanical properties make them attractive for use in energy-efficient devices. In particular, a defect in the otherwise pure atomic carbon structures of nanotubes can emit single photons of light—a…

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